Process of melting



(No Model.)

B. A. COLBY. rnocnss 0P MBLTING, REFINING, AND CASTING METALS. No. 428,552. Patented May 20, 1890.

(5144mm E a's M My. @45

UNITED STATES PATENT QFFICE.

ED\VARD A. COLBY, OF NET/V HAVEN, CONFECTIOUT.

PROCESS OF MELTING, Rsrmgmc, AND oAs'rm'c "METAL-s.

To all whom it mag concern.-

Be it known thatI, EDWARD A. COLBY, a citizen of the United States, residing at New Haven, in the county of New Haven, in the State of Connecticut, have'invented certain new and useful Improvements in the Process of Melting, Refining, and (lasting Metals, of p which the following isa specification.

The invention relates to a method of meltxo ing, refining, and casting metals and nonmetallic substances.

The object of the invention is, primarilytpto melt, refine, or cast certain substances 'by electricity, and, secondly, to accomplish this under conditions which prevent deterioration of the metals while in a state of fusion, as by carrying on the process in a rarefied or artificial atmosphere The invention is of especial value in refi-n-' :6 ing and casting various metals in such manner that they will be free from blisters, pin- 1 holes, and occluded gases. Many of the metals have a high absorptive capacity for gases. This affinity is especially manifested at ele- 2 5 vated temperatures between the more ref ractory metals and hydrogen. Upon solidifica tion from the molten state a port-ion ofthese occluded gases is retained; but the larger portion is expelled violently if the metal cools 3o rapidly, sometimes ejecting molten particles, and creates in its exitininute fissures, termed pin-holes, or, in the aggregate, blisters throughout the mass. Castings made in the ordinary manner are therefore unhomogene- 3 5 ous in structure. This defect may be greatly magnified in castings of platinum and its allied refractory metals, which are melted with the oxyhydrogen flame, because, it be- 'ing impracticable to supply the compound 40 gases of the flame in the exact proportion of theiraflinitive volumes, an excess of hydrogen is generally present, free to be absorbed by the molten metals. An unhomogeneous struct-. ure, while perhaps of slight importance in any metallic mass, may entail serious conse quences when, as for example, the metal is drawn into a fine wire, as any defect in structure then becomes a hidden source of trouble. This is especially true where, as in the man- .ufacture of incandescent electric lamps, it is of the utmost importance that the platinum l and iron core F by air-spaces (Z. The block sealed in the glass should be of uniform densrscmca'non forming pm of Letters Patent No. 428,552, dated my 20, 1890.

Application filed December 17, 1887. Serial No. 258,172- (No-model.) I

sity. In this specific casethe slightest fissure in the platinum wires serves as areservoi'r and possibly as a channel for the entrance of gases capable of destructive union with the carbon filaments.

Many laboratory experiments have beenmade to produce a high grade of metallic castings for specific uses; but the beneficial results attained have involved methods too expensive for commercial adoption. a

This invention consists in heating metals and refining them .in a closed and gas-exhausted containing-vessel by means of the inductive action of electric currents, and in casting them while so heated and deprived of occluded gases into ingots.

The invention will be described in connec tion with the accompanying drawings, in which- Figure 1 is a vertical transverse section, and Fig. 2 isa plan view, of a device adapted to the purpose of the invention.

Referring to the figures, A represents a suitable-stand, upon which the furnace Bis supported. This furnace may be carried upon a trunnion a. It consists, in thisinstance, of an outer casing 11', containing an inductive device, presently to be described; The case b is provided with a cover 11 which maybe securely .fastened down by bolts bi. The" cover and case thus form an air-tight chamher. Within this chamber there is placed the induction device, and this consists of a primary coil P, a secondar conductor S, and a core F. The coil P-is designed to be included in the circuit of a generator K, delivering an alternating, intermittent, or pulsatory electric current. This coil consists 0f.suitab1e conducting-wireinsulated with fire-proof material-such, for instance, as asbestos. It is wound upon a spool c, which is pfreferablyof refractory insulating materialsuch, forin: stance, as slate. Within the coil P there is placed an ann ular blockEof non-electricconducting material-such, for 'instaime as fires; clay or lime capable of withstanding great' heat. This may be separated from the coil contains an annular groovee,in which there is set the annular trough or receptacle S, which is designed to receive the material to be heat-ed or melted or otherwise operated upon. Such material may be various chemical substances, organic or inorganic, having no chemical affinity for the containing-rcceptacle. The trough Sis designed to consti' tute the secondary coil of the converter or induction coil; but if the substance to be acted upon isitself a condnctorot' electricity, italso may constitute, partially or entirely, the sec-- ondary coil, in which latter case the trough is not used.

For the purpose of better conveying the electric' energy from the coil P to the conductor S the core F is employed. This may consist of soft-iron wires, which are preferably electrically insulated from each other to agreateror less extent. These wires extend through the center of the block E. and across the bot-tom of the coil 1, and thence around the sides and across the top, as shown. The top of the block E is preferably covered by a disk F, which is removable; but when it is in position it serves to complete the magnet-circuit through the core F. The disk F is also composed, preferably, of radiating insulated soft-iron wires. The under side of the disk F may be lined with some refractory niaterial-such, for instance, as fire-clay or lime.

The disk F is constructed with one or more openings f for the purpose of allowing the material to be operated upon to be readily placed in the annular space e. The disk nay be secured in place by a nut or washer f passing around the cent-ral portion of the core F.

It is designed that the primary coil 1 shall be connected in an electric circuit by means of conductors L and If, leadingfrom the generator K or other suitable source of alternating, intermittent, or pulsatory currents of high potential. Currents will thus be induced in the secondary circuit of the annular trough or receptacle S. Such current will cause this trough to be heated and thus any material-such as metals and non-conducting chemical substances or liquids-placed in the trough, as indicated at s, will be raised to a temperature dependent upon that of the trough. As there is but a single turn of the' secondary circuit, the current will be of low intensity but of great quantity, and thus the temperature may be raised to any required degree. 4

Complete control of the temperature is secured by any of the usual devices for regulating the current in the primary circuit. Usually it is necessary that the volume of the substance contained in the receptacle S should be such that when heated or fused it shall exceed the capacity of that receptacle, so that no injury will come to it. from overheating.

This device is especially useful in melting non-conductors of electricity; but it may also be employed in connection with conducting materials. When the metals themselves are to serve as the secondary circuit, the trough may be dispensed with in some instances, and the currents induced directly in the metals.

The cover 5 may be applied to the case b after the substance is in position, and if it is desired to treat. the substance in a rarefied atmosphere the air may be exhausted by means of a vacuinn-pump applied to a tube N leading through the cover. After the natural air has been exhausted, together with the gas which comes from the substance when heated, additional gas may be forced by a pump into the chamber through the inlet N, preferably leading into the lower portion of the containing-vessel S, and thus up through the melted substance. Gases may be employed which have a chemical afiinity for the impurities contained in the substance being operated upon, or which form, with the substances under treatment, definite desired compounds. The resultant gaseous products are then removed from the chamber bythe vacuum-pump. 'hen the substance .has been sutficiently treated, the entire furnace may be turned upon the trunnion (L by means of a handle or lever If, and, if desired, the vacuui'n-punip may still be in operation. The substance will then be caused to flow into a mold M, which is fastened to the cover and held in position above one of the openings f, by means of a support n, fastened to the cover.

A peep-hole r, closed by aglass disk, may bejormed in the cover at a suitable point for observing the operation.

I claim as iny. invention 1. The hereinbeforc-deseribed process of electrically,mclting and refining metals and other substances, which 'consists in heating the entire mass of the substance in a retaining-receptacle by inductively establishing electrical currents in the substance or the receptacle, and thus heating the substances to and retaining them at the desired temperature.

2. The hei'einbefore-described process of electrically melting and refining conducting substances, which consistsin establishing electric currents within the same by inductive action until the metal is brought to a molten condition and then casting the same.

3. The hereinbeforc-described process of melting electric cond nctiu g substances, which consists in creating a rarefied or equivalent atmosphere in a. closed chamber, heating the entire mass of the substance to the point of -fusion in such atmosphere by inductivelyestablishing electrical currents therein, and casting or operating upon the substances in such atmosphere.

In testimony whereof I have hereunto subscribed my namev this 12th day of December, A. D. L587.

EDWARD A. COLBY.

Witnesses:

'DANL. \V. EDGECOMR, JENXIE P. ASHLEY.

ITO 

